A major problem of sustaining freshwater supply from freshwater lens is the invasion of saline groundwater into a fresh groundwater body. In many coastal areas saltwater intrusion has led to well closure and reduced freshwater supply. Furthermore, in the future saltwater intrusion is expected to increase due to sea level rise, climate change, land subsidence, and increasing population density in coastal areas. In the Netherlands, these stresses will also have a severe impact on the fresh coastal groundwater reserves. In view of this, a research project within the Dutch research program ’Knowledge for Climate’ was defined in 2010, aimed at: 1. Improving the insight into the modeling of freshwater lenses. 2. Defining measures to increase freshwater supply from freshwater lenses. In this thesis the results of four studies related to these objectives are presented.